Auxin status of transformed Solanum plants in relation to their tolerance to 2,4-D and productivity

The gene ugt, coding for maize UDPG-transferase, was introduced into the pl ants of four cultivars of Solanum tuberosum L. and S. demissum L. using a t ransconjugate of a triparental cross between Agrobacterium tumefaciens A699 (gus-int, 35S), Escherichia colt XL1-Blue with a pBluescript (ugt), and E, colt K802 with pRT104 (gus, 35S, ugt). IAA biosynthesis and its binding to glucose in vitro were more active in the transformed plants than in the co ntrol plants. Transformation enhanced the rate of plant elongation, the tol erance to 2,4-D, and the productivity. In transformed potato, cv. Borodyans kii, treatment with 2,4-D (100 mg/l) doubled the yield of tubers. These fav orable characteristics were: maintained for four years in vegetatively prop agated material. The introduction of genes improving the auxin status of pl ants is supposed to shift the optimal concentration of endogenous auxin to a higher level.